Projectile



March 21, 1961 E. w. READ 2, 5,710

PROJECTILE Filed Nov. 1a, 1958 INVENTOR. E LLIS W. READ 19% g g-4QJLQ/VA MQ I- ATTORNEYS= PROJECTILE Ellis W. Read, Philadelphia, Pa.,assignor to the United States of America as represented by the Secretaryof the Army Filed Nov. 18, 1958, Ser. No. 774,787

6 Claims. (Cl. 10266) (Granted under Title 35, U.S. Code (1952), see.266) The invention described herein may be manufactured and used by orfor the Government for governmental purposes without the payment to meof any royalty thereon.

The invention is a continuation-impart of my co-pending patentapplication, Serial No. 655,450, filed April 26, 1957, now abandoned,and relates to jacket-clad, armorpiercing projectiles of the incendiarytype. More particularly, this invention relates to enhancing theuniformity of sensitivity and performance, at long ranges, when theprojectile has lost a substantial part of its original velocity, andwide angles of impact, of jacket-clad, armorpiercing projectiles whichare designed to act against thinwalled targets, such as gasoline tanks.

The art, in the U.S. patent application of Thomas Q. Ciccone, Serial No.720,802, filed March 11, 1958, now Patent 2,900,914 dated August 25,1959 for Incendiary Projectile, by maintaining closely a controlledspace and geometry, teaches a means of obtaining long-range senstivityin projectiles other than jacket-clad projectiles.

However, the teachings of Ciccone could not be employed in jacket-cladprojectiles. Primarily this is so because as a jacket is formed over therear end of the solid penetrator of an armor-piercing projectile, it hasa tendency to stretch throughout its length and thus distort the closedimensions which must be maintained to insure uniform sensitivity, thenose portion of the projectile, which houses a preformed impactsensitive mixture, must maintain its dimensions to close tolerancessince this mixture functions as a result of crystal shear.

I have overcome the above difficulty by providing a jacket-cladprojectile with an inner jacket in the nose fabricated from asubstantially harder material than the outer jacket, and providing aconstruction in which the contours of both jackets are matched andplaced in tightfitting contact over a portion of the projectileamounting to approximately 30% of the length of the entire projectile.Now when the rear end of the outer jacket is being spun over the rearend of the solid penetrator, the tightfitting contact between thejackets for a major portion of the length of the inner jacket as shownin the drawing and the difference in their relative hardnesses preventelongation of the outer jacket from occurring in the forward portionand, instead, allow such elongation to occur only in that portion of theouter jacket to the rear of the area of contact between the jackets.Thus the nose of the outer jacket is prevented from creeping toward theinner jacket and the desired spacing is maintained between the noseportions of the jackets.

Another result of providing an inner jacket which is harder than theouter jacket is that, upon impact of the projectile, when the outerjacket is deformed, the inner jacket does not move. Thus the innerjacket acts as an anvil and the movement of the outer jacket toward theinner produces the crystal shear necessary to ignite the sensitivemixture between them.

In addition, the inner jacket contributes to safety in assembly of theprojectile. The conical section between 2,975,710 Patented Mar. 21, 1961the jackets must be closely controlled so as to insure ignition uponimpact, yet cannot be so tight as to produce premature ignition when theinner jacket is inserted in the outer jacket and presses upon thesensitive mixture.

The jackets are constructed to include sufficient clearance to containthe preformed sensitive mixture without producing undue pressure. Thetight-fitting contact and the difference in hardness between the jacketsinsures correct positioning of the compounds without producing unduepressure on the sensitive mixture.

This invention can best be understood by referring to the drawings inwhich:

Fig. 1 is a view, drawn to an enlarged scale and partly 'broken away andpartly sectiOnedQdf the forward end of the projectile; and,

Fig. 2 is a view, drawn to an enlarged scale and partly broken away andpartly sectioned, of a preferred embodiment of the forward end of theprojectile.

Figs. 1 and 2 show the forward end of the projectile which comprises anouter jacket 5 which has a cylindrical body portion 6, an ogive shapednose portion 7 and a nose tip 8. This outer jacket is made of any one ofa number of known materials, such as gilding metal copper and 10% Zinc)so that it is easily deformed when the projectile strikes a target.

Coaxially disposed within the outer jacket is a solid body portion orpenetrator 10, having a cylindrical portion 11 and a nose portion 12.Also within the outer jacket, coaxially disposed between the solidpenetrator and the outer jacket, is an inner jacket 15 fabricated from amaterial substantially harder and less easily deformable than that usedfor the outer jacket (such as 1020 coldworked steel) and having at leastfour openings 16 through its wall near the tip 17. The inner jacket isthinwalled to enable it to be deformed and spread by the penetrator whenthe projectile strikes the target. The shape of the rear portion of theinner jacket is matched to that of the outer jacket so as to permittight-fitting contact between the jackets over the distance I, which asshown in the drawing extends over a major portion of the length of theinner jacket.

In Fig. l the inner jacket 15 partitions the closed space between theouter jacket 5 and the solid penetrator 10 into two coaxial cuplikechambers 20 and 21, which chambers are in communication with each otherthrough the openings 16 in the inner jacket. The shape of the forwardportion of the inner jacket produces a space 20 of increasingcross-section toward the tip of the projectile, and insures uniformsensitivity over the angle a.

In Fig. 2, the forward portion of the inner jacket 15 is offset radiallyinward to produce a space 20 of uniform radial depth, thus insuringuniform sensitivity over the larger angle 13.

Chamber 20, preferably, contains an explosive 22 sensitive to impact,and chamber 21 contains incendiary material 23. When the projectilestrikes a target, the nose 7 of the outer jacket is deformed toward theinner jacket 15, thereby causing explosive 22 to ignite. Fire fromexplosive 22 passes through the openings 16 and ignites incendiarymaterial 23. Meanwhile both jackets 5 and 15 are opened by penetrator 10which then acts against the target in the usual manner.

Thus by reason of this invention, proper dimensions and tolerances aremaintained since elongation of the outer jacket takes place only in itsrear portion leaving unaffected the critical spacing, and thus thesensitvity, of the forward portion of the projectile. The spacingselected depends upon such factors as safety in handling, range,projectile caliber and velocity, and the type of explosive andincendiary material carried by the projectile; the spacing beingvariable from about 0.016 inch in small caliber projectiles to about0.125 inch in caliber 60 projectiles.

For example, in the 60 caliber projectile, the critical distance betweenthe tips of the jackets is 0.125 inch, held to tolerance as small as$00015 inch, The total ength of the projectile is approximately 2.8inches'and the length of tight-fitting contact between the jackets isapproximately 0.8 inch, with a tolerance of 0.003 inch. Tests indicatethat such a projectile is consistently effective against 0.020 inchlaminar duraluminum at a range of 175 yards, whereas prior projectileswould function consistently only against 0.040 inch laminar duraluminurnat the same range. The length of the tight-fitting contact i between theinner and outer jackets depends on a number of factors including theinitial degree of tension in the outer jacket, the types of metalsselected for the jackets, the tightness of the fit of the outer jacketover the penetrator throughout the cylindrical portion of the projectileand the degree of clearance in the critical nose tips of the jackets.

By the term armor piercing is not meant the penetration of heavy platebut rather the piercing of the thinner plates used around gasoline tankson aircraft. After the projectile of this invention has been slowed invelocity at long ranges, it is enabled to retain its sensitivity toignite its primer and incendiary materials that causes it to be anadvance in the art.

I claim:

1. In an armor-piercing projectile, the combination of a solidpenetrator, an outer jacket cone-shaped in its forward portion, and aninner jacket substantially harder than the outer jacket, said innerjacket having a portion in tight-fitting contact with said outer jacketin the tapered portion of said outer jacket said portion intight-fitting contact extending over a major portion of the inner jacketlength to confine any elongation of the outer jacket to a rear portionand adjacent cylindrical portion when the outer jaccet is formed overthe rear end of the projectile, whereby a criticalnose tip separationbetween these jackets is substantially unchanged, said inner jacketbeing axially spaced from said outer jacket to create a first cuplikechamber in the forward most portion of the projectile 'between the outerand inner jackets, the distance between the tips of the jackets varyingfrom about 0.016 inch in a 22 caliber projectile to about 0.125 inch ina projectile of caliber, the spacing of said inner jacket also creatinga second larger cuplike chamber between said inner jacket and saidpenetrator, said first chamber being loaded with an impact sensitiveexplosive and said second chamber being loaded with an incendiarymixture, said chambers communicating with each other through a pluralityof holes in the forward portion of the wall of the inner jacket so ,thatat impact a flame generated in the explosive can be transmitted to theincendiary mixture.

2. A projectile according to claim 1 in which the tightfitting contactbetween said jackets in a forward tapered portion is about 30% .of thetotal length of the projectile.

3. A projectile according to claim 2 in which the impact sensitivematerial is of substantially uniform radial depth longitudinally of thefirst chamber.

4. An incendiary projectile haying a body portion, a soft metal jacketcontiguous said body portion and having a generally conical forwardportion, an inner conical jacket of harder and less easily deformablematerial than the outer jacket, said inner jacket being in tight-fittingcontactswith said outer jacket for a major portion of the length of theinner jacket and abutting said body portion to maintain a precisespacing between said jackets in a nose portion of said projectile, anincendiary material within said inner jacket, an impact sensitiveexplosive between said jackets in the projectile nose, the inner jacketbeing perforate adjacent the projectile nose for passage of flame fromsaid impact sensitive explosive to ignite said incendiary material afterdeformation of a nose portion of the outer casing, whereby anyelongation of the outer jacket on bending a rear portion is largelyconfined to a portion of the outer jacket-in rear of the inner jacketwithout danger of reducing the spacing between said jackets in a noseportion of said projectile.

5 A projectile according to claim 4 in which the outer jacket portiontightly fitting around said inner jacket is prestressed in tension.

6. A projectile according to claim 4 in which the space between saidjackets occupied by said impact sensitive explosive is of substantiallyuniform radial depth.

References Cited in the file of this patent FOREIGN PATENTS 310,766Germany June 17, 1920

